1. Field of the Invention
The present invention relates to a method for controlling the movement of a moveable first object relative to a second object, and namely with the aid of optical sensing of the second object or a part thereof by means of an optical sensing system, with recognition of a pre-determined pattern and/or a structure present on the second object, wherein corresponding structures are stored in a memory device, and wherein the first and the second objects are approached from a position in which they are spaced apart into engagement with one another.
The present invention also relates to an apparatus for controlling the movement of a moveable first object relative to a second object, with drive and control devices for at least one of the objects, a pattern memory device and a pattern recognition device, and an optical sensing device for patterns and/or structures selected for or applied to the second object.
2. Discussion of Related Art
Corresponding methods and apparatus are known from so-called robotics and robot technology. With the method and the apparatus from which the present invention proceeds, for example, a tool fitted on the end of a robot arm must engage with an object, which itself can be moveable, so its position is not exactly defined from the outset but must first be sensed by an optical sensing device in order to bring the robot arm and the tool fitted onto it into engagement with the second object concerned in a well-directed manner. The fact that the position of the second object with which the first object or part of the first object has to be brought into engagement is not defined from the outset, differentiates such methods and apparatus, for example, from other automated machines such as, for example, machine tools with tool changing devices in which different tools are arranged in a tool magazine at precisely defined positions, so an automatic tool change can take place without the respective tools having to be optically sensed.
With other methods and apparatus, for example, a tool, a reading head or another device is continuously passed at a substantially fixed distance above the surface or parts of the surface of a second object. Here too, parts of the first object can be in engagement with parts of the second object. However it is not the procedure of bringing the first object closer to the second object which is controlled, but simply the movement of the parts engaged with one another relative to one another, for example, the movement of a welding device along a welding path, wherein the seam site of the parts to be welded together is optically sensed and continuously followed. During this movement control, no approaching takes place, but instead the distance is kept constant with the aid of an appropriate feed-back control system.